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In vitro modeling of matrix vesicle nucleation: synergistic stimulation of mineral formation by annexin A5 and phosphatidylserine.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2007 Sep 07; Vol. 282 (36), pp. 26035-45. Date of Electronic Publication: 2007 Jul 05. - Publication Year :
- 2007
-
Abstract
- Annexins A5, A2, and A6 (Anx-A5, -A2, and -A6) are quantitatively major proteins of the matrix vesicle nucleational core that is responsible for mineral formation. Anx-A5 significantly activated the induction and propagation of mineral formation when incorporated into synthetic nucleation complexes made of amorphous calcium phosphate (ACP) and Anx-A5 or of phosphatidylserine (PS) plus ACP (PS-CPLX) and Anx-A5. Incorporation of Anx-A5 markedly shortened the induction time, greatly increasing the rate and overall amount of mineral formed when incubated in synthetic cartilage lymph. Constructed by the addition of Ca(2+) to PS, emulsions prepared in an intracellular phosphate buffer matched in ionic composition to the intracellular fluid of growth plate chondrocytes, these biomimetic PS-CPLX nucleators had little nucleational activity. However, incorporation of Anx-A5 transformed them into potent nucleators, with significantly greater activity than those made from ACP without PS. The ability of Anx-A5 to enhance the nucleation and growth of mineral appears to stem from its ability to form two-dimensional crystalline arrays on PS-containing monolayers. However, some stimulatory effect also may result from its ability to exclude Mg(2+) and HCO(-)(3) from nucleation sites. Comparing the various annexins for their ability to activate PS-CPLX nucleation yields the following: avian cartilage Anx-A5 > human placental Anx-A5 > avian liver Anx-A5 > or = avian cartilage Anx-A6 >> cartilage Anx-A2. The stimulatory effect of human placental Anx-A5 and avian cartilage Anx-A6 depended on the presence of PS, since in its absence they either had no effect or actually inhibited the nucleation activity of ACP. Anx-A2 did not significantly enhance mineralization.
- Subjects :
- Animals
Annexin A2 chemistry
Annexin A2 metabolism
Annexin A5 metabolism
Annexin A6 chemistry
Annexin A6 metabolism
Bicarbonates chemistry
Bicarbonates metabolism
Calcium metabolism
Cations, Divalent chemistry
Cations, Divalent metabolism
Chondrocytes chemistry
Chondrocytes metabolism
Crystallization
Emulsions chemistry
Humans
Magnesium chemistry
Magnesium metabolism
Phosphatidylserines metabolism
Annexin A5 chemistry
Calcification, Physiologic
Calcium chemistry
Membranes, Artificial
Models, Biological
Phosphatidylserines chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 0021-9258
- Volume :
- 282
- Issue :
- 36
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 17613532
- Full Text :
- https://doi.org/10.1074/jbc.M701057200